Car top carriers and means for attaching them to the top of a car including supporting legs fastened to the ends of the bar for supporting the bar in spaced relation to the top are old in the art; however, in so far as known no supports are provided which enable mounting a carrier bar to the top of a vehicle having a very high arched roof portion and, in particular, vehicle tops provided with a blister such as is common to campers. The lack of such adequate supporting means makes it impossible to use conventional carriers in conjunction with such vehicles. It is the purpose of this invention to provide especially designed carrier brackets to enable mounting carrier bars to the tops of vehicles of the kind referred to and especially to provide brackets for this purpose which are of very simple construction and designed when attached to the vehicle to prevent forward and rearward tipping of the load carried thereby due to fast acceleration and deceleration of the vehicle; to provide a bracket structure which is adjustable heightwise for accommodating itself to tops of different height; and to provide a bracket structure which can be securely clamped to the gutters at the sides of the top.